A good method of coming up with a plot for your adventures is to adapt them from sources such as movies.
Of course, you need to obfuscate this fact, lest your players figure out what movies you've borrowed
the plot from. You can do this by modifying parameters of the movie plot, but there's an easier way.
Borrow from movies you haven't seen yet. Better still, from movies you know your players
haven't seen yet - movies that haven't even been released! You can extract some information
from trailers and rumour sites to get the basic outline of a plot. Fill in the details any way you
like, and you've generated an adventure which is guaranteed to be new and exciting for your players.
And since you've had to invent some of the story wholesale, it might even remain unfamiliar after they've seen the movie, too.

In the real world of the Avatars & Avifauna universe, of course, the Avatar movie doesn't exist. That's the premise of this
entire comic, after all. But most of the other things we know and love (such as blue-skinned space-catgirls) do, albeit modified by the
lack of Avatar:

Sam Worthington is known (barely) for doing voiceovers for poorly selling computer games, but gains widespread fame after his appearance in the first
Futurama movie.

Sigourney Weaver is known primarily for her humorous role in Galaxy Quest.

Nerdy guys make YouTube videos of themselves using bows and arrows in forest green clothing instead of painted blue.

Without the success of Avatar to spark interest in CGI effects extravaganzas, Firefly was never revived
with a movie and a new series, and remains an obscure short-running TV show.

Titanic was never made into a film. Historical drama fans never had it so good.

The major CGI world background that pervades all of Western culture is WALL-E, despite it never being much good.
The original film was remade recently into a new, updated television series with a bigger budget, high-tech computerised special effects, and edgy writing.
And it sucked.

Throughout the 2000s and 2010s, all the greatest CGI Hollywood blockbusters were big-budget romantic comedies.

Vision-Impaired Transcript

GM: The attack choppers begin their attack on the Na'vi village.Neytiri: Awesome! We counter-attack!Jake: You don't stand a chance. I've told them all about your defences. I'm gonna be rich!Neytiri: What? Who are you?Jake: I'm a spy for the Marines...Jake: {text box narration for flashback sequence} It started with us growing an avatar for my body...Dr. Augustine: We hybridised Na'vi DNA with your own to create an avatar with their physical characteristics but your facial features.Dr. Augustine: Now we'll transfer your neural patterns into the body with this psychic vortex.Jake: Wow, that's pretty good technobabble for a...Dr. Augustine: What?Jake: Uh, nothing.Dr. Augustine: Just relax and let your mind go blank.Dr. Augustine: That shouldn't be hard for you.